R&S AFQ100A
Bit Error Rate Measurements - BERT Block
1401.3084.32 4.66
E-3
Bit Error Rate Measurements - BERT Block
Introduction
The instrument contains an integrated bit error rate tester which makes it possible to evaluate a signal
demodulated and decoded by a DUT by measuring the bit error rate. A known PRBS-modulated data
sequence (PRBS = pseudo random binary sequence) is sent to the DUT. The PRBS data sequence is
decoded by the DUT and sent to the instrument in the form of clock and data signals. The bit error rate
tester of the instrument synchronizes to the known PRBS sequence and counts the bit errors. The ratio
obtained by dividing the number of error bits by the total number of bits is the BER.
The dialog for adjusting the BERT settings can be accessed in the block diagram via the
BERT
function
block or by selecting
BERT
in the
Edit
menu.
The equipment layout for the basic unit (R&S AFQ with R&S AFQ-B10/B11 waveform memory option)
includes the option R&S AFQ-K80 (Bit Error Rate Tester).
The
BERT
interface is located on the rear panel (see chapter 1, section "
Besides the data and clock input, it provides other inputs with which the user data containing the PRBS
sequence can be masked.
Test setup
The following figure shows the test setup for the bit error rate measurement. The data used to drive the
DUT can be generated by an R&S modulation generator or an user-defined external source. The
instrument can generate any externally computed modulation signals that were created using e.g.
WinIQSIM2
software.
A known PRBS sequence must be used for the bit error rate measurement.
(PRBS) Data
(RF / I/Q)
Clock
Demodulated Data
Restart
Data Enable
BERT
Interface
R&S Modulation
Generator
DUT
Fig. 4-3
Test setup for bit error rate measurement. The DUT is driven using a known data sequence. It demodulates the
data and sends it together with a clock signal to the instrument. The Data Enable signal marks the user data of the signal. The
restart signal for restarting the PRBS calculation is only important for the bit error rate measurement.
